Lane Departure Assist and Steering Wheel grip

where do I place my hands on the steering wheel on the prime?

 

Most anywhere except the 11 to 1 o'clock positions(top of the wheel). At first I thought you actually had to wrap your fingers around it, but it appears to only need a decent mass of flesh extremely close to the wheel's surface. If you wrap your fingers around the wheel but don't actually touch it, it will still register it. Or you can place the majority of your hand or thigh on or close to the wheel and it will register. A single finger or two won't do it unless the rest of the hand is also close(or you use that finger to slightly move the wheel and trigger the steering angle sensor).

If you really want to know exactly what works and doesn't, I'd recommend finding a nice stretch of fairly empty highway and test for yourself.